Cytomegalovirus (CMV) is probably the most ubiquitous of the pathogenic viruses. Virtually all of the people living in the developing countries become infected with CMV early in life, and CMV infects over half the population in the developed countries of the world. CMV may remain essentially inactive in the body following an initial infection and may flare in to an active infection any time, most frequently when the body's immune system is compromised to a greater or lesser degree by disease, radiation or chemotherapy, drug therapy, surgical trauma, etc.
CMV is frequently associated with, and may be a causative or contributing factor in, life-threatening disease in individuals with suppressed immune systems, and can be a principal causative factor in pneumonia, neurological disorders, febrile illness, ocular disease and hepatitis. CMV infection is a serious limiting factor in the transplantation of organs, tissues and cells and the transfusion of blood and plasma from one individual to another. The kidney transplant patient runs a high risk of contracting serious, and not infrequently fatal, CMV infection from CMV introduced by the transplant organ. Recipients of whole blood, plasma, bone marrow, cornea, cardiac, and semen run a serious risk of CMV infectious disease, the risk being multiplied where the immune system of the recipient is suppressed to prevent rejection of the foreign organ or cells, or where immunosuppresion is present from natural causes.
CMV is frequently associated with Pneumoncystis carinii and may cause or contribute to encephalitis and colitis and may be associated with Kaposi's sarcoma in AIDS patients. CMV is so ubiquitous in the blood and organs of donors who, frequently, exhibit no symptoms of infection, and its direct and contributory effects in infectious diseases is so pervasive and subtle that a CMV infection is to be presumed if another causative agent cannot be established.
There are no proven cures or generally effective drugs for the treatment of CMV infections. Certain drugs, e.g. ganciclovir, has been shown to have limited effectiveness in the treatment of certain CMV infections, e.g. CMV retinitis, but has little effect in the treatment of CMV pneumonia. Live attenuated CMV vaccine has been developed but may not protect against infection by natural CMV, and there is a real risk that the attenuated CMV may reactivate during pregnancy and infect the fetus.
While a method of preventing, or even reducing the likelihood of transmitting CMV via transplant or transfusion organs, tissues, cells or fluids would be of enormous benefit to medical science, the present invention is not limited to treatments to inhibit CMV infection and is applicable to other classes of virus.
CMV is a member of the human herpesvirus (HV) group, which are responsible for much of mankind's discomfort and pain. The herpesviruses represent a very large, clearly defined group of viruses which are responsible for, or involved in, cold sores, shingles, a venereal disease, mononucleosis, eye infections, birth defects and probably several cancers. Three subfamilies are of particular importance. The alpha subfamily includes HV-1 (herpes virus simplex 1) which causes cold sores, fever blisters, eye and brain infections, HV-2 (herpes virus simplex 2) which cause genital ulceration, and HV-3 (HV varicella zoster) which causes chicken pox, shingles and brain infections. The beta subfamily includes HV-5, the principal member of which is CMV discussed above. The gamma subfamily includes HV-4 (Epstein-Barr) which causes infectious mononucleosis and is involved in Burkitt's lymphoma and nasopharyngeal carcinoma. Additional possibly pathogenic herpes viruses no doubt exist, one type of which, HV-6, of unknown pathogenicity has been identified. (Niederman, J. C. et al, The Lancet, Oct. 8, 1988, 817). There is evidence that the methods of this invention are effective in inhibiting the transmission of infections caused by many and perhaps all of the pathogenic herpes viruses.
While blood bankers have instituted rigid criteria for exclusion of potential donors in high risk categories, this is not a satisfactory solution to the most significant threat to face the health care community in many decades. Institution of HIV testing has blood products safer, but the complete elimination of HIV contaminated blood and blood products has not been possible using present knowledge and technology. The ELISA test, for example, misses approximately 1 in 200 (0.5%) HIV infected donors, and there is no certain method for excluding donor carriers of hepatitis, AIDS, and other infectious viruses. Increasing efforts are exerted to improve the safety of the blood supply such as retrovirus screening using surrogate markers, screening for HIV and other retroviruses with attention to population surveillance for newer agents, cleaner methods of extracting specific blood components by monoclonal antibody techniques and DNA methodologies, development of recombinant DNA products which by-pass the need for plasma derived clotting factors for administration to hemophiliacs. While careful screening of donors, followed by antibody testing reduces the risk of AIDS and other virus contaminated plasma, such methods require testing supplies and trained technicians which are not available and are too expensive for use in such places as central Africa and other third-world countries where AIDS infects up to one-third of the population. A simpler and less costly method of handling plasma is required in such areas of the world.
A photodynamic method has also been evaluated as a means of eradicating viral contaminants (Matthews J. L. et al, Transfusion, 28,1 1988) but has not been proved to be generally effective and safe. While donor-screened, heat-treated factor VIII products appear to be effective in protecting the hemophilia population, no methods are known to guarantee the safety of plasma. For the blood plasma recipient, however, the only reasonably reliable safety procedures are programs allowing for self donation prior to elective surgery by the donor and the use of plasma from designated donors, but such programs are incredibly difficult logistically. In spite of heroic efforts to meet the challenge of an AIDS-virus-contaminated plasma supply, an imperative need continues to exist for a method for treating blood plasma for use in transfusion. It is apparent from the foregoing discussion that a method of killing or inactivating pathogenic viruses in organs, tissues, cell and fluids intended for transfusion or transplantation would be an enormous advance in medicine. It is to this major national and worldwide health care challenge that the present invention is directed.
Licorice is a well-known flavoring agent. In addition to its use as a flavoring agent, licorice has long been a common folk medicine for the treatment of sore throats. While not widely known, various extracts of and preparations derived from licorice, e.g. glycyrrhizin and its derivatives, principally the salts of glycyrrhizic acid, have also been used to a limited degree for many years as an orally administered medication for the treatment of peptic ulcers (Chandler, R. F., Can. Pharm. J., V118, No.9, 1985), and oral administration of glycyrrhizin contemporaneously with saponin antiinflamatory agents has been reported to inhibit sapon and saponigen hemolysis (Segal, R. et al., Biochem. Pharmacol. 26, 7 1977).
The family of compounds of interest are, chemically, referred to as triterpenoids. The specific triterpenoids of interest are, principally, derived as extracts or derivatives of glycyrrhiza and are referred to here as GTPD compounds. GTPDs have been evaluated extensively in vitro, and have been administered orally, intramuscularly and intravenously. No significant toxicity from limited, short term administration of glycyrrhizin has been reported. Adverse reactions have been reported in certain instances of prolonged oral ingestion and a slight relapse after rapid discontinuation of intravenous administration of Stronger Neo-Minaphagen C (SNMC) solution, glycyrrhizin (0.2%) cystein (0.1%) and glycine (2) was attributed to the steroid ring in glycyrrhizin (Fujisawka K. et al., Asian Med. J. (Japan) 23,10 1980). Dosages of SNMC as high as 60 ml/day (.about.12 mg/dy of glycyrrhizin) have been reported (Iwamura K., Therapiewoche (W. Germany) 30,34 1980).
Inactivation of viruses, in vitro, under certain conditions, has been reported (see, e.g., Pompei R., Exprientia (Switzerland) 36/3 1980). Such anti-viral activity as GTPD compounds sometimes exhibit has been attributed to reverse transcriptase-inhibitory activity (Nakashima, H. et al., Jpn. J. Cancer. Res. 78,8 1987) and to enhancement of interferon-gamma production (Shinada, M. et al., Proc. Soc. Exp. Biol. 181,2 1986), but the exact mechanism of the anti-viral function has not been confirmed.
Dargan, D. J., and Subak-Sharpe, J. H., (J. Gen. Virol., 1985-1986) reported antiviral action of carbenoxolone and cicloxolone on herpes simplex virus. Their dose-response experiments showed cicloxolone sodium or carbenoxolone sodium interfered with the HSV replication cycle and reduced the infectious virus yield by 10,000- to 100,000-fold, cicloxolone being the more potent anti-herpes agent, but no consistent effect on HSV DNA synthesis was identified. Some inhibition of cellular DNA synthesis was observed, but this was relatively slight.
Csonka, G. W. and Tyrrell, D. A. (Br. J. Vener. Dis. 1984, 60 (3) p178) undertook a double blind clinical study to compare the efficacy of carbenoxolone and cicloxolone creams with placebo in initial and recurrent herpes genitalis and reported significant differences in the time to disappearance of pain and the healing of lesions using cicloxolone, but carbenoxolone showed insignificant beneficial effect.
GTPDs have also been evaluated therapeutically as anti-viral agents in the chemotherapy of acquired immune deficiency syndrome (AIDS) (Ito, M., Yamamoto, N., Yakaguaku Zasshi (Japan) 188,2 1988), treatment of Epstein-Barr virus (EBV) infections (Van Benschoten, M. M., Am. J. Acupunct, 16,1 1988) and in the treatment of chronic hepatitis (Fujisawa, K. et al., Asian Med. J. (Japan), 23,10 1980).
The anti-viral activity of GTPDs varies so unpredictably as to preclude any generalized statements as to whether such compounds have general anti-viral effect or even as to whether such compounds will generally have anti-viral value as to any given virus. While GTPD drugs do, in some environments and under some conditions, exhibit some activity against some viruses, no anti-viral therapy based on GTPDs or in vitro anti-viral application of GTPDs has been generally accepted. The AIDS-causing viruses, HIV-I and HIV-II, are the first retroviruses identified as pathogenic in man. While HIV are more fragile than most infectious viruses and are susceptible to destruction by most virus-inactivating methods, such as heating, use of detergent compounds, etc., these methods also damage cells, e.g. the red blood cells, and, therefore, are not suitable for use in treating blood. In addition, any substance added to blood will, unless removed, remain in the blood, and must, therefore, be non-toxic when administered intravenously. Removal of added toxins from blood is, at best, complex and expensive and may not be feasible or possible without serious damage to blood components.
The addition of detergents to various blood fractions has been described. My European Patent Specification 0 050 061, published Dec. 11, 1985, in which the term "detergent" is equated with the term "amphophil" to encompass cationic, anionic and nonionic detergents, describes the addition of various detergents to plasma protein products and suggests the addition thereof to other blood derivative products to inactivate virus and for other purposes, followed by the removal of the detergent from the product. High concentrations of detergents, from 0.25 to 10%, were required the process described in the European patent specification.
Bosslet and Hilfenhause, European Patent Specification 0 278 487, discloses that high concentrations of selected detergents inactivate certain envelope viruses.
Neurath and Horowitz, e.g. U.S. Pat. Nos. 4,540,573, 4,481,189, and 4,591,505, indicate, however, that detergent alone is not effective as an antiviral agent in blood plasma and related products. In spite of these teachings, however, it seems safe to conclude that at least some classes of detergents in high concentrations in some types of blood derivatives do have some inactivating effect. The extent and efficacy of such procedures seems open to considerable doubt, however.
The major constituent of plasma is albumin whose primary role is that of osmotic regulation; it is responsible for 75-80% of the osmotic pressure of plasma. Albumin also serves important roles in the transport of small molecules such as drugs.
An important feature which segregates albumin from other colloids as well as crystalloids is its unique ability to bind reversibly with both anions and cations; hence, albumin can transport a number of substances including fatty acids, hormones, enzymes, dyes, trace metals, and drugs. Substances which are toxic in the unbound or free state are generally not toxic when bound to albumin. This binding property also enables albumin to regulate the extracellular concentration of numerous endogenous as well as exogenously administered substances.
Albumin in general has three types of binding sites (one for acidic, one for basic, and one for neutral compounds), and it plays a critical role in the binding and transport of lipid and lipid-soluble material. Albumin binds with and transports many administered drugs. Because of the phenomenon of mutual displacement of similar type substances, adverse drug interactions may occur. This phenomenon may have important ramifications during disease states such as sepsis, burn injury, and circulatory shock due to a number of etiologies, especially in conjunction with treatment with drugs which may be toxic at high concentrations.
Human serum albumin is believed to be a scavenger of oxygen-free radicals, an important phenomenon which also extends to scavenging of radicals required for lipid peroxidation.
Albumin is a potent scavenger of oxygen radicals. Concentrations of human serum albumin below those present in normal human plasma completely inhibit the inactivation of .alpha..sub.1 -antiproteinase (.alpha..sub.1 -proteinase inhibitor [a.sub.1 -PI], .alpha..sub.1 -antitrypsin) by hypochlorous acid.
Preliminary work in the endotoxemic sheep adult respiratory distress syndrome (ARDS) model also demonstrated that pretreatment with human serum albumin markedly attenuates the 300% to 400% increases in pulmonary lymph flow, transvascular protein clearance, and transvascular protein flow which normally occurs during endotoxemia. UNIQUE FEATURES OF ALBUMIN: A BRIEF REVIEW, Thomas E. Emerson, Jr., Ph.D., Critical Care Medicine, Vol. 17,No. 7 (1989).
Treatment with human serum albumin to bind toxic products generated during inflammatory disease states has not received widespread attention. However, a few studies and the inherent ability of albumin to bind with numerous toxic plasma substances support the concept.
Albumin is critical for the transport of numerous compounds, especially non-water soluble ones. It binds with iron and lipids and other potentially toxic substances, e.g., bilirubin. This albumin acts as a buffer to prevent increases in potentially cytotoxic endogenous lipid-soluble substances by binding with, and thus limiting, increases in plasma and interstitial fluid concentrations of these substances.
In addition to displacement of on albumin-bound drug by another, endogenous substances may also alter significantly the unbound or "free" plasma and interstitial fluid concentration of a drug. For example, as the concentration of bilirubin increases in certain disease states, a drug which occupies the same binding site as bilirubin will be displaced by the bilirubin, and the plasma concentration of the free drug will increase, possibly to toxic levels. Also, as the plasma concentration of albumin decreases, the plasma and interstitial fluid concentration of the unbound (free) drug will increase.
It is known that albumin binds to glycyrrhizic triterpenoids. Carbenoxolone is a potent ulcer-healing drug which is extensively bound to plasma proteins and therefore has the potential for displacement interaction. Carbenoxolone has been shown to be bound to human serum albumin in vitro at a different class of binding site to many other drugs and does not potentiate the pharmacological activity of warfarin, tolbutamide, chlorpropamide or phenytoin in the rat. Thornton PC; Papouchado M; Reed PI Scan J Gastroenterol Supp 1980, 65 p35-9.
The binding of glycyrrhizin to human serum and human serum albumin (HSA) was examined by an ultrafiltration technique. Specific and nonspecific bindings were observed in both human serum and HSA. The association constants (K) for the specific bindings were very similar: 1.31.times.10.sup.5 M.sup.-1 in human serum and 3.87.times.105M.sup.-1 in HSA. Glycyrrhizin binds to only the albumin fraction. It was concluded that the glyrrhizin-binding sites in human serum exist mainly on albumin and glyrrhizin binds to specific and nonspecific binding sites at lower and higher concentrations than approximately 2 mM, respectively. Ishida S; Sakiya Y; Ichikawa T; Kinoshita M; Awazu S, Chem Pharm Bull (Tokyo) 37 (1). 1989. 226-228.
Comparison by equilibrium dialysis of plasma protein binding sites for carbenoxolone in people under 40 yr of age and in people over 65 yr of age showed that the number of binding sites was reduced in the elderly and this fall was associated with a reduction in plasma albumin levels. Hayes M J; Sprackling M; Langman M, Gut 18 (12) 1977 1054-1058.
Albumin has been used as an emulsion stabilizer oil-and-water emulsion injectable medical preparations, e.g. fluorbiprofen, Mizushima et al U.S. Pat. No. 4,613,505, Sep. 23, 1966; as a binding molecule for tryptophan, Pollack U.S. Pat. No. 4,650,789, Mar. 17, 1987; with chemical modification as complexing agents for cholesterol derivatives, Arakawa U.S. Pat. No. 4,442,037, Apr. 10, 1984; as conjugates with enzyme chemically linked to an antibody, Poznansky U.S. Pat. No. 4,749,570, Jun. 7, 1988; and as chemically coupled conjugates of leukotrienes, Young, et al U.S. Pat. No. 4,767,745, Aug. 30, 1988.
Human serum albumin is a remarkable protein which performs numerous tasks critical to maintenance of the milieu interieur. The best known functions of albumin involve regulation of transvascular fluid flux and hence, intra and extravascular fluid volumes and transport of lipid and lipid-soluble substances. However, it is also involved in a number of other vital functions, some of which have only recently been suggested and perhaps others which are as yet unrecognized. Among recognized unique features of albumin are: a) binding, and hence, inactivation of toxic products; b) regulation of the plasma and interstitial fluid concentrations of endogenous and exogenously administered substances and drugs; c) involvement in anticoagulation; d) maintenance of microvascular permeability to protein; and e) scavenging of free radicals and prevention of lipid peroxidation. This latter property may prove to be critically important, particularly in inflammatory disease states in which free radicals are thought to be a major culprit in direct damage due to tissue oxidation and indirect tissue damage due to inactivation of important antiproteinases such as .alpha..sub.1 -PI and AT-III. See UNIQUE FEATURES OF ALBUMIN: A BRIEF REVIEW, Thomas E. Emerson, Jr., Ph.D., Critical Care Medicine, Vol. 17, No. 7 (1989).
The major hazard in producing fractions from large pools of plasma is the transmissions of virus, the most serious, being hepatitis. This is a danger both for the recipient of the fractions and for the workers in fractionation plants. It has been shown that fractionation workers, particularly those engaged in the preparation of plasma pools, are at high risk of developing hepatitis B. The high risk products are fibrinogen, AHF, and prothrombin complex. The low risk products are ISG, PPF, and albumin. The lack of infectivity of PPF and albumin is attributable to heating the final products at 60.degree. C. for 10 hours.
It is now required in the United States that all donors of blood or plasma be tested for the presence of hepatitis B surface antigen by radioimmunoassay or reversed passive hemagglutination. This screening reduces but does not prevent the transmission of hepatitis B virus. A major problem is the transmission of non-B hepatitis, for which there is not screening test. Recent evidence indicates that non-A, non-B hepatitis also invokes a viral agent.
Another hazard of plasma fractionation is the partial denaturation of some fractions such as ISG, caused by the fractionation methods. These denatured proteins may have toxic effects or may be immunogenic in the recipients. Among these undesirable side effects is the significant degree of loss of biological competence and the loss or blockage of many binding sites on albumin are lost by the inherent denaturation resulting from this pasteurization or heating process. According to present technology, the disadvantages of denaturation are more than compensated for by the increased stability and potency of concentrated fractions, but there remains a great need for a fully bio-competent albumin.
The safest source of albumin, in many instances, is the patient's own blood, and it is known to remove the blood, accomplish a partial fractionation of the blood, treat one fraction of the blood and return the treated fraction to the patient. Ishizaki et al U.S. Pat. No. 4,839,055, Jun. 13, 1989, describe a method for treating a blood which involves separating the blood withdrawn from a patient's body, mixing the condensed blood and the low molecular weight protein with a substitute liquid and returning the combined liquid into the patient's body.